It has long been recognized that full utilization of computers requires convenient devices for man-machine communication. Among such devices are manual keyboards, computer graphics terminals, and voice-recognition systems. By contrast, the most widespread medium for communication between man and man, apart from speech, is the printed page. It has been a goal, ever since the development of the digital computer, to provide convenient man-machine interfaces such that the conveying of information to and from a computer is effected with minimum expense, training time, and distraction to the user thereby to establish greater utilization of the computing power afforded by digital computers. In the past, keyboard actuated systems have been utilized as input devices, as well as such devices as punched cards, optical readers, and graphics tablets.
It will be appreciated that the above mentioned input devices involve auxiliary equipment which can be costly or bulky. Moreover, with keyboard-oriented devices, entry of information frequently is based on a formal man-machine dialogue which may impose obtrusive or annoying mental steps upon the user. Note that mental manipulations required for the entry of information in this manner are somewhat removed from the normal way in which human beings communicate via the written word. In addition, keyboard entry requires a certain amount of typing skill. The disadvantages of graphical input devices include the cost of the hardware and lack of easy portability.
In another class of input/output (I/O) devices, fiber optics have been utilized in the past to provide a coding system for the entry of information into a computer. For instance, fiber optics have been utilized as illustrated in U.S. Pat. No. 3,612,888 for reading a punched card containing information. In this patent, the optical fibers are used not only to detect the presence or absence of light coming through the card at a particular location, but are also utilized to establish a predetermined code by virtue of the routing of the optical fibers.
Moreover, encoding has been accomplished by embedding fiber optic elements in a card such as illustrated in U.S. Pat. No. 3,728,521. In this patent, fibers exposed to the edges of the card are individually illuminated by light sources. Coding for the card is accomplished by internally severing a predetermined fiber and by providing occluding material at the severed point, thereby to prevent light from traveling from one end of the fiber to another. The non-illuminated ends of the fibers are provided with detectors so as to permit decoding of the state of the fiber optic transmission path.
One of the problems with the encoded card described in U.S. Pat. No. 3,728,521 is that the encoding is accomplished prior to final lamination of the fibers into the card. The coding is therefore fixed at the time of manufacture and is not readily alterable by a user either to change the code or to enter information other than that which was originally encoded. Thus, while fiber-optic coded cards have been utilized in the past as input devices, the coding has been fixed or at least not readily alterable by the user. This is also true, for instance, with respect to fiber optic coded keys which are precoded and utilized in the manner of a traditional key.